Exposed lens plate luminaires typically comprise LED modules mounted in a housing or supporting mechanism with no additional shielding or protection provided to the light emitting surface of the LED module. As such, an exposed lens plate luminaire may have fewer parts than other lighting arrangements, resulting in a lower cost luminaire with increased light output and an improved beam profile.
Known LED modules employed in exposed lens plate luminaires comprise an LED light source; an optically transmissive element (such as a lens plate) and an electrical connection element. Optionally, such LED modules are known to further comprise additional thermal management elements, e.g. a heat sink. The LED light source typically comprises a printed circuit board (PCB) with a plurality of LEDs mounted thereon, said LEDs being adapted to output light from a light-emitting surface of the printed circuit board. Due to the absence of a protective element, the LED module itself should preferably be self-sealing to prevent the ingress of foreign contaminants such as dust or water, in accordance with IP66 and IP67.
One known solution to this issue comprises sealing the optical plate to a heat sink positioned on a non-light-emitting surface of the LED light source (i.e. a surface on the reverse of the LED light source, opposite and parallel to the light emitting surface). Another known method is to extend the optical plate around the LED light source to the non-light-emitting surface of said light source and seal the optical plate thereon. However, this requires a dedicated housing to mount these modules, needing to accommodate the parts of the optical plate that extend to this the reverse surface. Other modules may comprise sealing the optical plate to the light-emitting surface of the LED module; however, this may cause a reduction in the optical efficiency of the LED module.
US2013088863A1 discloses a LED module comprising LEDs mounted on a MCPCB which is inserted into a transparent, cylindrical cover, covering a portion of the interface between layers at a side surface of the MCPCB.